Lake Irwin aging valve vault and schematic of valve and piping
Underwater Rover Camera shot of existing water intake

Town of Crested Butte: Source Water Resilency Project

Source Water Resilency Project objective is rehabilitation of aging and/or debilitated raw water conveyance infrastructure with improvements to SEO regulations located in the historic mining town site of Irwin, which is approximately 7 miles west upstream of the Town of Crested Butte (Town) and at the head waters of Coal Creek.  The Town holds a 367-acre foot water storage right in Lake Irwin, which is critical for both the Town’s domestic drinking water supply and in stream flows in Coal Creek.

This project will improve access, operations and maintenance, and safety at the site.  In addition, the releases from this facility provide positive benefits to aquatic life and habitat, wildlife, recreation, downstream water rights (Town owned and agricultural), and CWCB instream flow rights.  Finally, recent dam breach modeling, geotechnical investigations, and condition assessments of the existing facility, which were performed by the design team, emphasize the need for the replacement of the Lake Irwin tunnel, valve and piping infrastructure.   


Engineering and Design: Carollo Engineers was awarded July 6, 2021 for 30%, 60%, 90%, and 100% design and engineering. Engineering included geotechnical investigation, defining the site conditions and condition assessment of the existing facilities which include:

  • Upstream submerged timber set tunnel constructed in 1877,
  • Concrete valve shaft with 16” gate valve constructed in 1935 to Coal Creek via a
  • A 16-inch 430-ft long outfall pipeline construction in 1986 to replace the collapsed outfall timber set tunnel.

This project involves stakeholder coordination involving Colorado Parks and Wildlife, US Forest Service (adjacent campground and traffic), State Engineer’s Office (dam coordination) and Dam Safety – Montrose Office.  

Construction: The project will be delivered as Construction Management at Risk, for which Moltz Construction was awarded a contract on January 7, 2022 for 60%, 90%, and 100% design review and Guaranteed Maximum Price GMPs.


Preliminary investigation included : 

  • Underwater Divers and Rover investigation of 1877 timber set tunnel
  • Geotechnical Investigation included bore holes 
  • Survey of the Town of Crested Butte's land and easement by Lake Irwin 


Videos from the Underwater Divers and Rover investigation are attached.   


Huge thank you to Colorado River District and Colorado Water Conservation Board for Design and Engineering grants and your support.  

Town has received important Local Grant support from Colorado Water Conservation Board of $25,000 for Design and $500,000 for Construction (March 20, 2023) with $350,000 from State Aging Infrastructure and $150,000 from the Gunnison round table basin.  We have received  $42,000 for Design and $300,000 for Construction (April 20, 2023) from Colorado River District and $50,000 for Construction from Upper Gunnison River Water Conservancy District (March 27, 2023). 

Town is working with Bennet's and Hickenlooper's staff for Colorado Congressional Directed Spending (CDS) for the Construction phase. Town plans to also apply for FEMA High Hazard Potential Dam (HHPD) Funding this Fall. Town will need both of these Federal Funds in order to move forward with the Coal Creek Dam (Source Water Resiliency Project).


Great Thanks to Colorado District River for this 2 minute video of Lake Irwin Valve and Piping project  Link Here






Lake Irwin Raw Water Infrastructure Intake What the Underwater Rover Camera sees! Sonar not shown. Underwater rover investigation of Lake Irwin raw water infrastructure intake 1877 timber set tunnel prior to 1935 valve that connects it via 1986 pipe to Coal Creek.
Lake Irwin Raw Water Infrastructure Intake 2 Underwater diver fixes large hole at Lake Irwin raw water infrastructure, the plan is to replace this section entirely in 2023.
Lake Irwin Valve and Piping Pictures of Project Geotechnical, underwater rover and divers and preliminary design.